This project has been aimed at collecting information concerning the processes which bring about inflammation and the involvement of lymphocytes, macrophages and immune mediators in these processes. Experiments carried out this year have further examined the effects of pertussis toxin (PT) on lymphoid cells in culture. This bacterial product is a powerful adjuvant and it facilitates remarkably the induction of experimental autoimmune diseases. Our previous experiments have shown that PT stimulates lymphocytes and macrophages in culture. Experiments carried out this year have indicated that PT has a dual effect on these lymphoid cells. Thus, cultures of lymphocytes or macrophages which are stimulated by other agents are often inhibited by the addition of PT at doses which are simulatory to cultures with no other stimuli. This finding is in line with reports showing that, at certain circumstances, PT may both enhance and inhibit immune responses. This project is being phased out, in order to focus the Section's effort on issues which relate directly to the immunopathogenesis of ocular inflammatory diseases.